Determination of the effects of perinatal exposure to exogenous estrogens and progestins, singly and in combination, on mammary gland noduligenesis and tumorigenesis in female mice. The agents whose actions will be examined are diethylstibestrol (DES), 17 a-hydroxyprogesterone caproate (17-OHPC), the oral contraceptive Ovral and its component estrogen and progestin, ethinyl estradiol, and norgestrel. These substances are representative of compounds to which human offspring have been frequently exposed in utero (DES, 17-OHPEC, Ovral) and as neonates (Ovral).